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backport fixes for information leak within a KVM guest

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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
This commit is contained in:
Thomas Lamprecht 2020-01-31 13:14:32 +01:00
parent d8fae28c33
commit de6f4b1d95
6 changed files with 649 additions and 0 deletions
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1
patches/kernel/0006-x86-MCE-AMD-Allow-Reserved-types-to-be-overwritten-i.patch
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@ -66,6 +66,7 @@ known bank type can update smca_banks[].
Fixes: 68627a697c19 ("x86/mce/AMD, EDAC/mce_amd: Enumerate Reserved SMCA bank type")
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/kernel/cpu/mce/amd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

38
patches/kernel/0008-x86-kvm-Be-careful-not-to-clear-KVM_VCPU_FLUSH_TLB-b.patch Normal file
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@ -0,0 +1,38 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Date: Fri, 31 Jan 2020 08:06:40 -0300
Subject: [PATCH] x86/kvm: Be careful not to clear KVM_VCPU_FLUSH_TLB bit
CVE-2019-3016
CVE-2020-3016
kvm_steal_time_set_preempted() may accidentally clear KVM_VCPU_FLUSH_TLB
bit if it is called more than once while VCPU is preempted.
This is part of CVE-2019-3016.
(This bug was also independently discovered by Jim Mattson
<jmattson@google.com>)
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/kvm/x86.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 778b3a899769..92d8e4ebba16 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3393,6 +3393,9 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
return;
+ if (vcpu->arch.st.steal.preempted)
+ return;
+
vcpu->arch.st.steal.preempted = KVM_VCPU_PREEMPTED;
kvm_write_guest_offset_cached(vcpu->kvm, &vcpu->arch.st.stime,

111
patches/kernel/0009-x86-kvm-Introduce-kvm_-un-map_gfn.patch Normal file
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@ -0,0 +1,111 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Date: Fri, 31 Jan 2020 08:06:41 -0300
Subject: [PATCH] x86/kvm: Introduce kvm_(un)map_gfn()
CVE-2019-3016
CVE-2020-3016
kvm_vcpu_(un)map operates on gfns from any current address space.
In certain cases we want to make sure we are not mapping SMRAM
and for that we can use kvm_(un)map_gfn() that we are introducing
in this patch.
This is part of CVE-2019-3016.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
include/linux/kvm_host.h | 2 ++
virt/kvm/kvm_main.c | 29 ++++++++++++++++++++++++-----
2 files changed, 26 insertions(+), 5 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d41c521a39da..df4cc0ead363 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -758,8 +758,10 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn
kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn);
kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
int kvm_vcpu_map(struct kvm_vcpu *vcpu, gpa_t gpa, struct kvm_host_map *map);
+int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map);
struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn);
void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
+int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn);
unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable);
int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, int offset,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 91e56a9b0661..6614e030ae75 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1792,12 +1792,13 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
}
EXPORT_SYMBOL_GPL(gfn_to_page);
-static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn,
+static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn,
struct kvm_host_map *map)
{
kvm_pfn_t pfn;
void *hva = NULL;
struct page *page = KVM_UNMAPPED_PAGE;
+ struct kvm_memory_slot *slot = __gfn_to_memslot(slots, gfn);
if (!map)
return -EINVAL;
@@ -1826,14 +1827,20 @@ static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn,
return 0;
}
+int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
+{
+ return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map);
+}
+EXPORT_SYMBOL_GPL(kvm_map_gfn);
+
int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
{
- return __kvm_map_gfn(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn, map);
+ return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_map);
-void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
- bool dirty)
+static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot,
+ struct kvm_host_map *map, bool dirty)
{
if (!map)
return;
@@ -1849,7 +1856,7 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
#endif
if (dirty) {
- kvm_vcpu_mark_page_dirty(vcpu, map->gfn);
+ mark_page_dirty_in_slot(memslot, map->gfn);
kvm_release_pfn_dirty(map->pfn);
} else {
kvm_release_pfn_clean(map->pfn);
@@ -1858,6 +1865,18 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
map->hva = NULL;
map->page = NULL;
}
+
+int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
+{
+ __kvm_unmap_gfn(gfn_to_memslot(vcpu->kvm, map->gfn), map, dirty);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_unmap_gfn);
+
+void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
+{
+ __kvm_unmap_gfn(kvm_vcpu_gfn_to_memslot(vcpu, map->gfn), map, dirty);
+}
EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);
struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn)

292
patches/kernel/0010-x86-kvm-Cache-gfn-to-pfn-translation.patch Normal file
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@ -0,0 +1,292 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Date: Fri, 31 Jan 2020 08:06:42 -0300
Subject: [PATCH] x86/kvm: Cache gfn to pfn translation
CVE-2019-3016
CVE-2020-3016
__kvm_map_gfn()'s call to gfn_to_pfn_memslot() is
* relatively expensive
* in certain cases (such as when done from atomic context) cannot be called
Stashing gfn-to-pfn mapping should help with both cases.
This is part of CVE-2019-3016.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/x86.c | 10 ++++
include/linux/kvm_host.h | 7 ++-
include/linux/kvm_types.h | 9 ++-
virt/kvm/kvm_main.c | 98 ++++++++++++++++++++++++++-------
5 files changed, 103 insertions(+), 22 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index f68e174f452f..7c06343614a4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -678,6 +678,7 @@ struct kvm_vcpu_arch {
u64 last_steal;
struct gfn_to_hva_cache stime;
struct kvm_steal_time steal;
+ struct gfn_to_pfn_cache cache;
} st;
u64 tsc_offset;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 92d8e4ebba16..41fee3d359ab 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8936,6 +8936,9 @@ static void fx_init(struct kvm_vcpu *vcpu)
void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
{
void *wbinvd_dirty_mask = vcpu->arch.wbinvd_dirty_mask;
+ struct gfn_to_pfn_cache *cache = &vcpu->arch.st.cache;
+
+ kvm_release_pfn(cache->pfn, cache->dirty, cache);
kvmclock_reset(vcpu);
@@ -9602,11 +9605,18 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
{
+ struct kvm_vcpu *vcpu;
+ int i;
+
/*
* memslots->generation has been incremented.
* mmio generation may have reached its maximum value.
*/
kvm_mmu_invalidate_mmio_sptes(kvm, gen);
+
+ /* Force re-initialization of steal_time cache */
+ kvm_for_each_vcpu(i, vcpu, kvm)
+ kvm_vcpu_kick(vcpu);
}
int kvm_arch_prepare_memory_region(struct kvm *kvm,
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index df4cc0ead363..abfc2fbde957 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -728,6 +728,7 @@ void kvm_set_pfn_dirty(kvm_pfn_t pfn);
void kvm_set_pfn_accessed(kvm_pfn_t pfn);
void kvm_get_pfn(kvm_pfn_t pfn);
+void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache);
int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
int len);
int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
@@ -758,10 +759,12 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn
kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn);
kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
int kvm_vcpu_map(struct kvm_vcpu *vcpu, gpa_t gpa, struct kvm_host_map *map);
-int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map);
+int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map,
+ struct gfn_to_pfn_cache *cache, bool atomic);
struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn);
void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
-int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
+int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
+ struct gfn_to_pfn_cache *cache, bool dirty, bool atomic);
unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn);
unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable);
int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, int offset,
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index bde5374ae021..2382cb58969d 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -18,7 +18,7 @@ struct kvm_memslots;
enum kvm_mr_change;
-#include <asm/types.h>
+#include <linux/types.h>
/*
* Address types:
@@ -49,4 +49,11 @@ struct gfn_to_hva_cache {
struct kvm_memory_slot *memslot;
};
+struct gfn_to_pfn_cache {
+ u64 generation;
+ gfn_t gfn;
+ kvm_pfn_t pfn;
+ bool dirty;
+};
+
#endif /* __KVM_TYPES_H__ */
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6614e030ae75..f05e5b5c30e8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1792,27 +1792,72 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
}
EXPORT_SYMBOL_GPL(gfn_to_page);
+void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache)
+{
+ if (pfn == 0)
+ return;
+
+ if (cache)
+ cache->pfn = cache->gfn = 0;
+
+ if (dirty)
+ kvm_release_pfn_dirty(pfn);
+ else
+ kvm_release_pfn_clean(pfn);
+}
+
+static void kvm_cache_gfn_to_pfn(struct kvm_memory_slot *slot, gfn_t gfn,
+ struct gfn_to_pfn_cache *cache, u64 gen)
+{
+ kvm_release_pfn(cache->pfn, cache->dirty, cache);
+
+ cache->pfn = gfn_to_pfn_memslot(slot, gfn);
+ cache->gfn = gfn;
+ cache->dirty = false;
+ cache->generation = gen;
+}
+
static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn,
- struct kvm_host_map *map)
+ struct kvm_host_map *map,
+ struct gfn_to_pfn_cache *cache,
+ bool atomic)
{
kvm_pfn_t pfn;
void *hva = NULL;
struct page *page = KVM_UNMAPPED_PAGE;
struct kvm_memory_slot *slot = __gfn_to_memslot(slots, gfn);
+ u64 gen = slots->generation;
if (!map)
return -EINVAL;
- pfn = gfn_to_pfn_memslot(slot, gfn);
+ if (cache) {
+ if (!cache->pfn || cache->gfn != gfn ||
+ cache->generation != gen) {
+ if (atomic)
+ return -EAGAIN;
+ kvm_cache_gfn_to_pfn(slot, gfn, cache, gen);
+ }
+ pfn = cache->pfn;
+ } else {
+ if (atomic)
+ return -EAGAIN;
+ pfn = gfn_to_pfn_memslot(slot, gfn);
+ }
if (is_error_noslot_pfn(pfn))
return -EINVAL;
if (pfn_valid(pfn)) {
page = pfn_to_page(pfn);
- hva = kmap(page);
+ if (atomic)
+ hva = kmap_atomic(page);
+ else
+ hva = kmap(page);
#ifdef CONFIG_HAS_IOMEM
- } else {
+ } else if (!atomic) {
hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
+ } else {
+ return -EINVAL;
#endif
}
@@ -1827,20 +1872,25 @@ static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn,
return 0;
}
-int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
+int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map,
+ struct gfn_to_pfn_cache *cache, bool atomic)
{
- return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map);
+ return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map,
+ cache, atomic);
}
EXPORT_SYMBOL_GPL(kvm_map_gfn);
int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
{
- return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map);
+ return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map,
+ NULL, false);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_map);
static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot,
- struct kvm_host_map *map, bool dirty)
+ struct kvm_host_map *map,
+ struct gfn_to_pfn_cache *cache,
+ bool dirty, bool atomic)
{
if (!map)
return;
@@ -1848,34 +1898,44 @@ static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot,
if (!map->hva)
return;
- if (map->page != KVM_UNMAPPED_PAGE)
- kunmap(map->page);
+ if (map->page != KVM_UNMAPPED_PAGE) {
+ if (atomic)
+ kunmap_atomic(map->hva);
+ else
+ kunmap(map->page);
+ }
#ifdef CONFIG_HAS_IOMEM
- else
+ else if (!atomic)
memunmap(map->hva);
+ else
+ WARN_ONCE(1, "Unexpected unmapping in atomic context");
#endif
- if (dirty) {
+ if (dirty)
mark_page_dirty_in_slot(memslot, map->gfn);
- kvm_release_pfn_dirty(map->pfn);
- } else {
- kvm_release_pfn_clean(map->pfn);
- }
+
+ if (cache)
+ cache->dirty |= dirty;
+ else
+ kvm_release_pfn(map->pfn, dirty, NULL);
map->hva = NULL;
map->page = NULL;
}
-int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
+int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
+ struct gfn_to_pfn_cache *cache, bool dirty, bool atomic)
{
- __kvm_unmap_gfn(gfn_to_memslot(vcpu->kvm, map->gfn), map, dirty);
+ __kvm_unmap_gfn(gfn_to_memslot(vcpu->kvm, map->gfn), map,
+ cache, dirty, atomic);
return 0;
}
EXPORT_SYMBOL_GPL(kvm_unmap_gfn);
void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
{
- __kvm_unmap_gfn(kvm_vcpu_gfn_to_memslot(vcpu, map->gfn), map, dirty);
+ __kvm_unmap_gfn(kvm_vcpu_gfn_to_memslot(vcpu, map->gfn), map, NULL,
+ dirty, false);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);

125
patches/kernel/0011-x86-KVM-Make-sure-KVM_VCPU_FLUSH_TLB-flag-is-not-mis.patch Normal file
View File

@ -0,0 +1,125 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Date: Fri, 31 Jan 2020 08:06:43 -0300
Subject: [PATCH] x86/KVM: Make sure KVM_VCPU_FLUSH_TLB flag is not missed
CVE-2019-3016
CVE-2020-3016
There is a potential race in record_steal_time() between setting
host-local vcpu->arch.st.steal.preempted to zero (i.e. clearing
KVM_VCPU_PREEMPTED) and propagating this value to the guest with
kvm_write_guest_cached(). Between those two events the guest may
still see KVM_VCPU_PREEMPTED in its copy of kvm_steal_time, set
KVM_VCPU_FLUSH_TLB and assume that hypervisor will do the right
thing. Which it won't.
Instad of copying, we should map kvm_steal_time and that will
guarantee atomicity of accesses to @preempted.
This is part of CVE-2019-3016.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/kvm/x86.c | 49 +++++++++++++++++++++++++++-------------------
1 file changed, 29 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 41fee3d359ab..431e34965707 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2482,43 +2482,45 @@ static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu, bool invalidate_gpa)
static void record_steal_time(struct kvm_vcpu *vcpu)
{
+ struct kvm_host_map map;
+ struct kvm_steal_time *st;
+
if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
return;
- if (unlikely(kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.st.stime,
- &vcpu->arch.st.steal, sizeof(struct kvm_steal_time))))
+ /* -EAGAIN is returned in atomic context so we can just return. */
+ if (kvm_map_gfn(vcpu, vcpu->arch.st.msr_val >> PAGE_SHIFT,
+ &map, &vcpu->arch.st.cache, false))
return;
+ st = map.hva +
+ offset_in_page(vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS);
+
/*
* Doing a TLB flush here, on the guest's behalf, can avoid
* expensive IPIs.
*/
- if (xchg(&vcpu->arch.st.steal.preempted, 0) & KVM_VCPU_FLUSH_TLB)
+ if (xchg(&st->preempted, 0) & KVM_VCPU_FLUSH_TLB)
kvm_vcpu_flush_tlb(vcpu, false);
- if (vcpu->arch.st.steal.version & 1)
- vcpu->arch.st.steal.version += 1; /* first time write, random junk */
+ vcpu->arch.st.steal.preempted = 0;
- vcpu->arch.st.steal.version += 1;
+ if (st->version & 1)
+ st->version += 1; /* first time write, random junk */
- kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.st.stime,
- &vcpu->arch.st.steal, sizeof(struct kvm_steal_time));
+ st->version += 1;
smp_wmb();
- vcpu->arch.st.steal.steal += current->sched_info.run_delay -
+ st->steal += current->sched_info.run_delay -
vcpu->arch.st.last_steal;
vcpu->arch.st.last_steal = current->sched_info.run_delay;
- kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.st.stime,
- &vcpu->arch.st.steal, sizeof(struct kvm_steal_time));
-
smp_wmb();
- vcpu->arch.st.steal.version += 1;
+ st->version += 1;
- kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.st.stime,
- &vcpu->arch.st.steal, sizeof(struct kvm_steal_time));
+ kvm_unmap_gfn(vcpu, &map, &vcpu->arch.st.cache, true, false);
}
int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
@@ -3390,18 +3392,25 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
{
+ struct kvm_host_map map;
+ struct kvm_steal_time *st;
+
if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
return;
if (vcpu->arch.st.steal.preempted)
return;
- vcpu->arch.st.steal.preempted = KVM_VCPU_PREEMPTED;
+ if (kvm_map_gfn(vcpu, vcpu->arch.st.msr_val >> PAGE_SHIFT, &map,
+ &vcpu->arch.st.cache, true))
+ return;
+
+ st = map.hva +
+ offset_in_page(vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS);
+
+ st->preempted = vcpu->arch.st.steal.preempted = KVM_VCPU_PREEMPTED;
- kvm_write_guest_offset_cached(vcpu->kvm, &vcpu->arch.st.stime,
- &vcpu->arch.st.steal.preempted,
- offsetof(struct kvm_steal_time, preempted),
- sizeof(vcpu->arch.st.steal.preempted));
+ kvm_unmap_gfn(vcpu, &map, &vcpu->arch.st.cache, true, true);
}
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)

82
patches/kernel/0012-x86-KVM-Clean-up-host-s-steal-time-structure.patch Normal file
View File

@ -0,0 +1,82 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Date: Fri, 31 Jan 2020 08:06:44 -0300
Subject: [PATCH] x86/KVM: Clean up host's steal time structure
CVE-2019-3016
CVE-2020-3016
Now that we are mapping kvm_steal_time from the guest directly we
don't need keep a copy of it in kvm_vcpu_arch.st. The same is true
for the stime field.
This is part of CVE-2019-3016.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/include/asm/kvm_host.h | 3 +--
arch/x86/kvm/x86.c | 11 +++--------
2 files changed, 4 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7c06343614a4..f62f4ff5f4f4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -674,10 +674,9 @@ struct kvm_vcpu_arch {
bool pvclock_set_guest_stopped_request;
struct {
+ u8 preempted;
u64 msr_val;
u64 last_steal;
- struct gfn_to_hva_cache stime;
- struct kvm_steal_time steal;
struct gfn_to_pfn_cache cache;
} st;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 431e34965707..c059728f8a44 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2503,7 +2503,7 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
if (xchg(&st->preempted, 0) & KVM_VCPU_FLUSH_TLB)
kvm_vcpu_flush_tlb(vcpu, false);
- vcpu->arch.st.steal.preempted = 0;
+ vcpu->arch.st.preempted = 0;
if (st->version & 1)
st->version += 1; /* first time write, random junk */
@@ -2676,11 +2676,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if (data & KVM_STEAL_RESERVED_MASK)
return 1;
- if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.st.stime,
- data & KVM_STEAL_VALID_BITS,
- sizeof(struct kvm_steal_time)))
- return 1;
-
vcpu->arch.st.msr_val = data;
if (!(data & KVM_MSR_ENABLED))
@@ -3398,7 +3393,7 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
return;
- if (vcpu->arch.st.steal.preempted)
+ if (vcpu->arch.st.preempted)
return;
if (kvm_map_gfn(vcpu, vcpu->arch.st.msr_val >> PAGE_SHIFT, &map,
@@ -3408,7 +3403,7 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
st = map.hva +
offset_in_page(vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS);
- st->preempted = vcpu->arch.st.steal.preempted = KVM_VCPU_PREEMPTED;
+ st->preempted = vcpu->arch.st.preempted = KVM_VCPU_PREEMPTED;
kvm_unmap_gfn(vcpu, &map, &vcpu->arch.st.cache, true, true);
}